Portable, hand held, and/or disposable devices used to perform real time or near-real time medical, chemical, or biological assays (e.g., at the point of care, in the field, at a crime scene, in a laboratory, etc.) may enable a practitioner (e.g., a technician, an investigator, a paramedic, a soldier, a nurse, a doctor, a veterinarian, etc.), to apply one or more reagents to a sample taken from a subject (e.g., a sample obtained from the subject's throat, urine, feces, vagina, ear, wound, blood, etc.), from a surface of an object, from a water supply, etc. The practitioner may insert the sample into the device and may perform an assay operation on the sample by causing the device to deliver the one or more reagents to the sample, for example, to test for the presence of certain biological matter, chemicals, contaminants, etc.
Devices can be used to perform a particular assay operation by delivering multiple reagents, stored within the device, to the sample. The device may permit the reagents to be delivered to the sample in an order or manner that is different than a particular order or manner associated with the particular assay operation, which may cause the particular assay operation to be performed incorrectly.